1. Field of the Invention
This invention relates to a process for interchanging hydrogen and deuterium atoms in selected compounds using ion exchange resins. A compound containing a labile proton can be deuterated by the process of this invention, or alternatively a deuteron in a compound can be replaced by a proton.
2. Description of the Prior Art
Ion exchange, the reversible interchange of ions between a solid and a liquid phase without the permanent change in the structure of the solid, has found a wide variety of applications. For example, an ion exchanger is used in water softeners to exchange sodium for calcium, thus removing calcium from hard water and replacing it with an equivalent quantity of sodium. Ion exchange is also used for deionization of water, purification of chemicals, concentration of metal solutions, and separation of ionized materials to obtain non-ionized or slightly-ionized materials.
The ability to manufacture synthetic resins having either a particular characteristic or great versatility has resulted in their use in many industrial processes. One use for such synthetic ion exchange resins has been as packing material in gas chromatographic units. Gas chromatography is primarily a separation technique with widely known applications in analytical chemistry, and until recently it had been thought impractical to prepare compounds on a large scale using this technique. Previous use of gas chromatographic systems to prepare or extract compounds has been very limited.
Other methods are known for exchanging hydrogen for deuterium or increasing concentrations of deuterium from that found in natural sources. U.S. Pat. No. 3,900,557 to Strathdee describes a catalyst comprising a transition metal coordination complex anchored on a cross-linked polystyrene. The anchored catalyst is useful for promoting H-D exchange between deuterated forms of hydrogen-containing gas streams and liquid water or alcohols.
U.S. Pat. No. 3,681,021 to Mikovsky et al. relates to the production of heavy water by subjecting a mixture of H.sub.2 and H.sub.2 O to isotopic exchange with each other in the presence of a catalyst comprising a Group VIII metal on a resin support. The system is described as useful for the transfer of deuterium from hydrogen gas to water, followed by the recovery of deuterium from the thus-enriched heavy water.
U.S. Pat. No. 3,510,519 to Frejaville et al. relates to the preparation of deuterated compounds by contacting and reacting under non-turbulent countercurrent flow conditions two compounds wherein one of the compounds is in liquid form and the other is in gaseous form. Frejaville et al. rely on a greatly elongated uncatalyzed reaction zone to achieve H-D exchange.
Other known methods of producing deuterated compounds typically involve laborious separation procedures to isolate the desired product from others in a product mixture. Conventional substitutions and separation techniques are especially difficult when using compounds such as deuterium and hydrogen because they have very similar physical properties.